Date: Sat, 25 Oct 2014 19:45:46 +0200 From: Willem Jan Withagen <wjw@digiware.nl> To: Peter Grehan <grehan@freebsd.org> Cc: virtualization@freebsd.org Subject: Re: Bhyve building kernel....Just an observation Message-ID: <544BE1CA.6010300@digiware.nl> In-Reply-To: <544ADF08.4020706@freebsd.org> References: <544A083B.50007@digiware.nl> <544ADF08.4020706@freebsd.org>
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On 25-10-2014 1:21, Peter Grehan wrote: > Hi Willem, >> And then booted a 10-STABLE bhyve VM with all memory and processors >> assigned to the VM. So all the power could be available to the VM. > > You'll most likely want to keep some memory and processor resources > available for the host system. ZFS will need memory for ARC and CPU for > operations - if these aren't available, it will compete with bhyve's use > of CPUs, and there will be times when these are conflicting. Hi Peter, Thanx for the hint. The assumption that the performance difference is, is Disk-IO is at least not very obvious from the simple test. Both tests were running from a 6Gb tmpfs Dom0 had 16Gb Ram, and I limited DomU to 12G Ram. Tested it once in Dom0, and it takes ~ 5Gb of tmp store. It holds src and obj, and I see no disk traffic while building. Building kernel with just the default tmpfs (all avail mem + swap) takes 6:30 (zfs with ssd's) versus 5:30 (tmpfs) Running in DomU is get about the same difference: with ahci-hd/zfs backing 9:30 with tmpfs 8:30 So I would think the difference is not really in the IO-performance. But as usual: All other opinions more than appreciated. --WjW
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